Plasma arc carbonizer

ABSTRACT

A system and method for plasma arc anaerobic thermal conversion processing is provided to convert waste into bio-gas; bio-oil; carbonized materials; non-organic ash, and varied further co-products. The system and process supports a variety of processes, including to make, without limitation, carbon, carbon-based inks and dyes, activated carbon, aerogels, bio-coke, and bio-char, as well as generate electricity, produce adjuncts for natural gas, and/or various aromatic oils, phenols, and other liquids, all depending upon the input materials and the parameters selected to process the waste, including real time economic and other market parameters which can result in the automatic re-configuration of the system to adjust its output co-products to reflect changing market conditions. Plasma arc carbonizer off-gases produced during carbonization are supplied to a controlled heated column for refining and recovery of the carbonizer hot gases into distillates.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority of U.S. Provisional Patent ApplicationSer. No. 62/360,141 filed Jul. 8, 2016, which is incorporated herein byreference.

FIELD OF THE INVENTION

The present invention in general relates to a system for convertingwaste into useful co-products, including hydrocarbon based gases,hydrocarbon-based liquids, and carbonized material; and in particular tocarbonation systems using plasma arc units as heating sources.

BACKGROUND OF THE INVENTION

Pyrolysis is a general term used to describe the thermochemicaldecomposition of organic material at elevated temperatures without theparticipation of oxygen. Pyrolysis differs from other high-temperatureprocesses like combustion and hydrolysis in that it usually does notinvolve oxidative reactions. Carbonization in these instances operatesat less than 5 atomic % oxygen and typically less than 2 atomic % and isoften characterized by irreversible simultaneous change of chemicalcomposition and physical phase.

Pyrolysis is a case of thermolysis, and is most commonly used fororganic materials, and is one of the processes involved in charring.Charring is a chemical process of incomplete combustion of certainsolids when subjected to high heat. The resulting residue matter iscalled char. By the action of heat, charring reductively removeshydrogen and oxygen from the solid, so that the remaining char iscomposed primarily of carbon in a zero-oxidation state. Polymers such asthermoplastics and thermoset, as well as most solid organic compoundslike wood and biological tissue, exhibit charring behavior whensubjected to a pyrolysis process, which starts at 200-300° C. (390-570°F.) and goes above 1000° C. or 2150° F., and occurs for example, infires where solid fuels are burning. In general, pyrolysis of organicsubstances produces gas and liquid products and leaves a solid residuericher in carbon content, commonly called char. Extreme pyrolysis, whichleaves mostly carbon as the residue, is called carbonization.

The pyrolysis process is used heavily in the chemical industry, forexample, to produce charcoal, activated carbon, methanol, and otherchemicals from wood, to convert ethylene dichloride into vinyl chlorideto make PVC, to produce coke from coal, to convert biomass into syngasand biochar, to turn municipal solid waste (MSW), and other carbonaceousmatter into safely disposable substances, and for transformingmedium-weight hydrocarbons from oil into lighter ones like gasoline.These specialized uses of pyrolysis are called by various names,illustratively including dry distillation, destructive distillation, orcracking. Efficient industrial scale pyrolysis has proven to bedifficult to perform and requires adjusting reactor conditions tofeedstock variations in order to achieve a desired degree ofcarbonization.

Converting waste from a liability to an asset is a high global priority.Currently employed technologies rely on incineration to dispose ofcarbonaceous waste with useable quantities of heat being generated whilerequiring scrubbers and other pollution controls to limit gaseous andparticulate pollutants from entering the environment. Incompletecombustion associated with conventional incinerators and thecomplexities of operation in compliance with regulatory requirementsoften mean that waste which would otherwise have value throughprocessing is instead sent to a landfill or incinerated off-site atconsiderable expense. Alternatives to incineration have met with limitedsuccess owing to complexity of design and operation outweighing thevalue of the byproducts from waste streams.

To address this global concern, many methods have been suggested to meetthe flexible needs of waste processing. Most of these methods requirethe use of a waste processing reactor, or heat source, which aredesigned to operate at relatively high temperature ranges 200-980° C.(400 to 2200° F.) and allow for continuous or batch processing.

“Chain Drag Carbonizer, System and Method for the Use thereof” asdetailed in U.S. Pat. No. 8,801,904; the contents of which are herebyincorporated by reference, provides an apparatus and process foranaerobic thermal conversion processing to convert waste into bio-gas;bio-oil; carbonized materials; non-organic ash, and varied furtherco-products.

In the technology presented, any carbonaceous waste is converted intouseful co-products that can be re-introduced into the stream of commerceat various economically advantageous points. The carbonizer as disclosedhas utility to support a variety of processes, including to make,without limitation, carbon, carbon-based inks and dyes, activatedcarbon, aerogels, bio-coke, and bio-char, as well as generateelectricity, produce adjuncts for natural gas, and/or various aromaticoils, phenols, and other liquids, all depending upon the input materialsand the parameters selected to process the waste, including real timeeconomic and other market parameters which can result in the automaticre-configuration of the system to adjust its output co-products toreflect changing market conditions.

“Infectious Waste Disposal” as detailed in Patent Cooperation TreatyApplication PCT/US16/13067; the contents of which are herebyincorporated by reference provides a medical waste handling andshredding sub-system with a built-in oxidizer to eliminate potentialairborne infectious waste prior to converting the medical waste intouseful co-products, including hydrocarbon based gases, hydrocarbon-basedliquids, precious metals, rare earths (vaporization temperatures rangefrom about 1200° C. to about 3500° C.), and carbonized material in asystem having as its transformative element an anaerobic, negativepressure, or carbonization system. The system includes a sealedenclosure that houses a shredder that is fed by a vertical lift and/or abelt conveyor that supplies the infectious waste running from theexterior of the sealed enclosure to the shredder. The shredder furtherincludes a hopper to receive waste and a process airlock where shreddedwasted material accumulates and is transferred to the feed conveyor. Arubberized exterior flap permits containerized and bagged waste to enterthe sealed enclosure via the belt conveyor. The sealed enclosure may bemaintained at a negative pressure. A thermal oxidizer in fluidcommunication with the sealed enclosure and a hood acts to destroy anyairborne infectious matter from the sealed enclosure and any airborneinfectious waste collected by the hood. The thermal oxidizer may be runon a mixture of natural gas and reaction-produced carbonization processgases re-circulated to convert heat through the use of eitherconventional steam boilers or through Organic Rankin Cycle strategies tooperate electrical turbine generators, or in the alternative, toconventional or novel reciprocating engine driven generators. A feedconveyor transfers shredded material from the shredder to a carbonizer.

Another approach to improve upon the incomplete combustion associatedwith conventional incinerators is the use of plasma technology. Plasmais a form of ionized gas, where freely flowing electrons give positiveor negative charges to atoms, thus making plasma a highly efficientconductor of electricity and generator of heat. The heat generatingproperties of plasma are utilized in plasma gasification, a process thatcan break waste down to 1/300th of its original size by using ionizedgases to produce temperatures greater than three times the surfacetemperature of the sun. The plasma gasification process can safely treatalmost all forms of hazardous and non-hazardous wastes by breaking downthe waste matter into component molecules and producing a synthesis gas(syngas) which can be used as an industrial feedstock to producebiofuels, synthetic fuels, hydrogen, or simply as a fuel (replacingfossil fuels) to generate steam or electricity.

FIG. 1 illustrates a typical plasma assisted gasification system 10 fortreating inputted waste. The inputted waste, which may include anycombination of solid, liquid, and gaseous wastes, including bothhazardous and non-hazardous wastes is delivered into the feed system 12.Solid waste of the inputted waste is passed through a pre-treatmentprocess where the solid waste is shredded into smaller pieces to preventblockages in the feed nozzle 14. The waste is then passed through anairlock 16 which prevents gases from escaping into the atmosphere. Theplasma gasifier 18 is an insulated air-tight container with plasmatorches 20 at the base of the plasma gasifier 18 to provide the heatrequired to gasify the waste feed. The plasma torches 20 consume a verysmall portion of the total energy available from the feedstock (2-5% oftotal energy input) in providing part of the heat required to drive theendothermic gasification process. Partial combustion provides thebalance of heat required. Torch power is controlled by an automaticcontrol system, which adjusts the gasification conditions to accommodatethe potentially highly variable nature of the feedstock. A plasma arc iscontained within the body of the plasma torch 20, and therefore, thewaste material is not directly subjected to the plasma arc. Hence, theclassification of the process as plasma assisted gasification.Nonetheless, the plasma torches 20 facilitate operating temperaturesabove typical flame temperatures associated with combustion of the wastefeedstocks, and also in excess of the melting points of metals andinorganic materials. Either air or oxygen and/or steam is injected abovethe torches to provide a source of oxygen for the gasification processand control the H₂:CO ratio. Importantly, the gasification occurs in anoxygen starved environment, such that a combustible syngas product isproduced, rather than a non-combustible flue gas, which would be thecase if all the feed material was combusted.

Continuing with FIG. 1 any carbon based, or organic molecules that areinside the gasifier 18 become volatilized and are turned into synthesisgas 22 (syngas), which is a mixture of H₂, CO, and CO₂. Inorganiccompounds become vitrified, or melted down and converted into anobsidian like substance, and metals are melted down into a form of slag24. An overflow mechanism is used to control the amount of slag 24available in the chamber at all times, ensuring that enough slag 24 isleft to maintain the required high temperatures.

After leaving the gasifier chamber 18 the syngas 22 passes through aseries of filtration systems 26 where the syngas 22 is cooled by usingwater injection and is filtered of all particulate matter (which canthen be fed back into the plasma gasifier). The cooling process acts toprevent the formation of dioxins and furans as these undesirablecompounds are known to form within a specific temperature range. The gaswill then be reheated to create a series of catalytic reductions toreduce the amount of NOx and convert it into atmospheric nitrogen andwater. A series of scrubbers will then remove any acids, chlorides,fluorides, sulphates, phosphates, sodium and calcium.

A turbine may be connected to the process to generate electricity, whichcan be used to not only power the plant, but also provide an alternateclean source of renewable power. Cogeneration also referred to ascombined heat and power (CHP) is the use of a heat engine or a powerstation to simultaneously generate both electricity and useful heat. Allthermal power plants emit a certain amount of heat during electricitygeneration. The heat produced during electrical generation can bereleased into the natural environment through cooling towers, flue gas,or by other means. By contrast, CHP captures some or all of theby-product heat for heating purposes, or for steam production. Theproduced steam may be used for process heating, such as drying paper,evaporation, heat for chemical reactions or distillation. Steam atordinary process heating conditions still has a considerable amount ofenthalpy that could be also be used for power generation.

While there have been many advances in recovering useable byproductsfrom recycled waste there continues to be a need for further limitingemissions from the recycling and recovery process that further maximizesrecovered byproducts. Thus, there exists a need for a process of wastereaction that is efficient to operate to limit environmental pollutionin the course of such a conversion, and to produce useful co-productsthat aid the overall economic value of the process.

SUMMARY OF THE INVENTION

A system is provided for treating waste, that includes a carbonizer withone or more plasma arc units, where the carbonizer converts the waste touseable products, and resultant hot gases produced from the carbonizerare supplied to a thermal oxidizer.

A method is provided for treating waste with a plasma arc carbonizer,where the method includes adjusting a set of parameters of thecarbonizer based on waste feed stock to be inputted, loading the wastefeedstock into the carbonizer; and collecting useable byproductsobtained from the carbonizer.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention is further detailed with respect to the followingdrawings. These figures are not intended to limit the scope of thepresent invention but rather illustrate certain attributes thereof.

FIG. 1 is a prior art functional diagram of a plasma gasification systemthat converts inputted waste to synthesis gas;

FIG. 2 is a perspective view of a plasma arc carbonizer with a pistondriver for pushing containers of waste into the plasma heating zone inaccordance with embodiments of the invention;

FIG. 3 is a side perspective view of a chain drag carbonizer with plasmaarc heating sources in accordance with embodiments of the invention;

FIG. 4 is a perspective view of a plasma arc carbonizer with acontrolled heated column for refining and recovery of carbonizer hotgases; and

FIG. 5 is a flowchart of a process for refining off-gases that areproduced by a carbonizer in accordance with embodiments of theinvention.

DESCRIPTION OF THE INVENTION

An inventive system and method for plasma arc anaerobic thermalconversion processing is provided to convert waste into bio-gas;bio-oil; carbonized materials; non-organic ash, and varied furtherco-products. In the inventive technology presented herein, anycarbonaceous waste is converted into useful co-products that can bere-introduced into the stream of commerce at various economicallyadvantageous points. The present invention has utility to support avariety of processes, including to make, without limitation, carbon,carbon-based inks and dyes, activated carbon, aerogels, bio-coke, andbio-char, as well as generate electricity, produce adjuncts for naturalgas, and/or various aromatic oils, phenols, and other liquids, alldepending upon the input materials and the parameters selected toprocess the waste, including real time economic and other marketparameters which can result in the automatic re-configuration of thesystem to adjust its output co-products to reflect changing marketconditions. In a specific embodiment of the plasma arc carbonizer,off-gases produced during carbinization are supplied to a controlledheated column for refining and recovery of the carbonizer hot gases. Thecontrolled heated column performs hydro-carbon recycling, and acts as acracking tower that takes the carbonizer off-gas as a feedstock anddistills the off-gases into constituent parts under pressure andtemperature conditions where the feedstock evaporates and condenses intoa fractional column of distillates. The number of theoretical platesneeded to exact a desired level of separation is readily calculatedusing the Fenske equation.

Distillates extracted are appreciated to be a function of the chemicalnature of the feedstock and the carbonizer conditions. Illustrativedistillates include C2-C36 compounds of alkanes, alkenes, ethers,esters, phenols, aromatics, lignins, polycyclics; and substitutedversions thereof where the substituent in place of a hydrogen atom isfor example, a hydroxyl, an amine, a sulfonyl, a carboxyl, a halogen, ora combination thereof.

As used herein, the terms “carbonized material”, “carbonaceous product”and “carbonaceous material” are used interchangeably to define solidsubstances at standard temperature and pressure that are predominantlyinorganic carbon by weight and illustratively include char, bio-coke,carbon, activated carbon, aerogels, fullerenes, and combinationsthereof.

It is appreciated that a feedstock is readily treated with a variety ofsolutions or suspensions prior to carbonizer to modify the properties ofthe resulting inorganic carbon product. By way of example, solutions orsuspensions of metal oxides or metal salts are applied to a feedstock tocreate an inorganic carbon product containing metal or metal ioncontaining domains. Metals commonly used to dope an inorganic carbonproduct illustratively include iron, cobalt, platinum, titanium, zinc,silver, and combinations of any of the aforementioned metals.

It is to be understood that in instances where a range of values areprovided that the range is intended to encompass not only the end pointvalues of the range but also intermediate values of the range asexplicitly being included within the range and varying by the lastsignificant figure of the range. By way of example, a recited range offrom 1 to 4 is intended to include 1-2, 1-3, 2-4, 3-4, and 1-4.

Since a core element of the inventive process for refining off-gasesthat are produced by a carbonizer is carbonization, there are a widevariety of possible operating configurations and parameters to adjustproduct mixes and waste stream throughput. The system is readilyre-configured, and system operating parameters changed, some in realtime, to adjust co-product outputs and percentages thereof to reflecton-going market conditions. For illustrative purposes, wood, beforeentering the process, can have its moisture removed, but not so much asto “burst” the plant cells within the cellular structure of the wood,but rather to rendered contained water as steam and thus destroy thecellular fabric of the wood. The temperature range, duration ofexposure, mixing rate, and other factors claimed as part of theinventive process, machine and system of systems herein are thus focusedon controlling the many variables inherent in such anaerobic thermalconversion processes in order to produce results with utility for futureuse as opposed to just destruction.

System configuration in certain embodiments includes carbonizationprocess heat source generators that are plasma arc units. In a specificembodiment, the plasma arc generators are nitrogen based.Reaction-produced carbonization process gases, if present, may bere-circulated to operate the drag chain reactor motors, used to heatwater and generate steam for turbines or steam reciprocating engines orto supply subsequent distillation processes. The re-circulated heat insome inventive embodiments may also be used to preheat feedstock or toproduce electricity. The pre-processing heating system preheatsfeedstock material prior to entering the reactor tube.

A carbonization system in specific inventive embodiments also utilizes athermo-chemical reactor which may be a drag-chain reactor, or otherssuch as, but not limited to batch, continuous-stirred-tank, thermaloxidizers, or plug-in reactors.

Another important element of an inventive system is the use of anair-seal, which not only aids mixing and heat diffusion, but allowspressurization of, or the creation of a partial or complete vacuumwithin the reactor for various reasons, including preventing gaseouscontaminants from escaping the reactor, managing pressures, and managingthe flow of gases within the overall reactor and associated processingelements.

Referring now to the figures, FIG. 2 is a perspective view of a plasmaarc carbonizer 30 with one or more plasma arc generators 40, and apiston driver 34 for pushing containers of waste 36 into the plasmaheating zone 42 of the sealed enclosure 38. The sealed enclosure 38 maybe maintained at a negative pressure. An airlock 32 may be used tointroduce the containers of waste 36 into the sealed enclosure 38 toprevent gases from escaping and to maintain the atmospheric conditionswithin the process chamber of the sealed enclosure 38. The remainingsolids illustratively including metals, glass, and carbon by-productsare moved with the piston driver 34 to the drop slot 44 and collected inthe bin 46. The collected materials may then be separated, andnon-useable by-products may be reintroduced into the plasma arccarbonizer 30 for further processing. A thermal oxidizer 48 in fluidcommunication with the sealed enclosure 38 acts to destroy any airborneinfectious matter and pollutants from the sealed enclosure 38.

FIG. 3 is a side perspective view of a chain drag carbonizer 50 with oneor more plasma arc heating sources 40. Waste is inputted into an airlock32 that introduces the waste to a shredder 52 that deposits the shreddedwaste on to a conveyer 56. The conveyer 56 carries the shredded wasteinto a plasma heated sealed enclosure 54. A thermal oxidizer 48 in fluidcommunication with the sealed enclosure 54 acts to destroy any airborneinfectious matter and pollutants from the sealed enclosure 54.

FIG. 4 is a block diagram of a plasma heated system 100 with a plasmaheated carbonizer 102 with a controlled heated column 104 for refiningand recovery of by-products from carbonizer hot gases. The plasma heatedcarbonizer 102 may perform anaerobic thermal conversion processing withone or more plasma arc generators 40 to generate heat that convertsinput (arrow A1) illustratively including, but not limited to municipalsolid waste, infectious medical waste, and bitumen into useable products(arrow A8) such as bio-gas; bio-oil; carbonized materials; non-organicash. Non-useable output (arrow A9) from the plasma heated carbonizer 102may either be safely disposed of, or recirculated back into thecarbonizer 104 for further processing. The plasma heated carbonizer 102may be operative with a controlled heated column 104 for refining andrecovery of by-products from carbonizer hot gases as detailed in U.S.Pat. No. 8,801,904. Hot gases (arrow A2) generated by and in thecarbonizer 102 are feed to the controlled heated column(s) 104 forhydro-carbon re-cycling (cracking). Temperature cut points (zones)within the controlled heated column 104 are signified by outputs106A-106D that supply distillates represented by arrows A3, A4, and A5.Remaining hot gases or solids (arrow A6) that do not distill out as auseable by-product may either be further scrubbed and safely disposedof, or recirculated (arrow A7) into the carbonizer 102 for furtherprocessing.

FIG. 5 is a flowchart of a process 200 for treating waste with a plasmaarc carbonizer. The process 200 starts by adjusting the parameters ofthe plasma arc carbonizer based on waste feed stock to be inputted (Step202). Carbonizer parameters may illustratively include temperature,conveyor speed, dwell times, and atmosphere. In some inventiveembodiments, once the carbonizer is at the required temperature, wastefeedstock is loaded into the carbonizer (Step 204). Subsequently,useable byproducts obtained from the carbonizer are collected, andnon-useable outputs are either safely disposed of or reintroduced intothe carbonizer (Step 206).

As a person skilled in the art will recognize from the previous detaileddescription and from the figures and claims, modifications and changescan be made to the preferred embodiments of the invention withoutdeparting from the scope of this invention defined in the followingclaims.

1. A system for treating waste, the system comprising: at least oneplasma arc unit; a carbonizer heated by said at least one plasma arcunits and adapted to convert the waste to a useable product andresultant hot gases; and a thermal oxidizer in gaseous communicationwith said carbonizer to receive the resultant hot gases.
 2. The systemof claim 1 wherein the waste includes at least one of municipal solidwaste, infectious medical waste, or bitumen that optionally containsnon-reactive inorganics.
 3. The system of claim 1 wherein saidcarbonizer employs anaerobic thermal conversion processing to treat thewaste.
 4. The system of claim 1 wherein said carbonizer comprises athermo-chemical reactor that is one of a drag-chain reactor, batchreactor, continuous-stirred-tank reactor, rotating drum, thermaloxidizers, or plug-in reactor.
 5. The system of claim 1 wherein saidcarbonizer operates under a reduced pressure of a partial or completevacuum.
 6. The system of claim 1 wherein said at least one plasma unitoperates with a nitrogen based atmosphere.
 7. The system of claim 1wherein the useable products converted from the waste is one or more ofcarbon black, carbon-based inks and dyes, activated carbon, aerogels,bio-coke, bio-char, combustion feedstock to generate electricity,adjuncts for natural gas, aromatic oils, or phenols.
 8. The system ofclaim 1 further comprising: a sealed enclosure; and a piston driver forpushing one or more containers of waste into a plasma heating zone ofsaid sealed enclosure.
 9. The system of claim 8 further comprising: anairlock in mechanical communication with the sealed enclosure, where theairlock introduces the one or more containers of waste into the sealedenclosure to prevent gases from escaping and to maintain the atmosphericconditions within the sealed enclosure.
 10. The system of claim 8further comprising: a drop slot in said sealed enclosure; and acollection bin adapted to move remaining solids and carbon by-productsthat result from the treated waste with said piston driver to said dropslot for collection in the collection bin.
 11. The system of claim 1further comprising a controlled heated column adapted for refining andrecovery of the resultant hot gases into distillates.
 12. The system ofclaim 11 wherein the distillates comprise one or more of C2-C36compounds of alkanes, alkenes, ethers, esters, phenols, aromatics,lignins, polycyclics; and substituted versions thereof where thesubstituent in place of a hydrogen atom is for example, a hydroxyl, anamine, a sulfonyl, a carboxyl, a halogen, or a combination thereof. 13.A method of using the system of claim 1 for treating waste with saidplasma arc carbonizer, the method comprising: adjusting a set ofparameters of said carbonizer based on waste feed stock to be inputted;loading waste feedstock into said carbonizer; and collecting useablebyproducts obtained from the carbonizer.
 14. The method of claim 13wherein the adjustable set of parameters for said carbonizer include oneor more of temperature, conveyor speed, dwell times, or atmosphere. 15.The method of claim 13 further comprising safely disposing ofnon-useable outputs from said carbonizer or reintroducing thenon-useable outputs into said carbonizer.
 16. The method of claim 13further comprising supplying the resultant hot gases to a controlledheated column for distilling and refining and recovery into distillates.17. The method of claim 16 wherein the distillates include one or moreof C2-C36 compounds of alkanes, alkenes, ethers, esters, phenols,aromatics, lignins, polycyclics; or substituted versions thereof wherethe substituent in place of a hydrogen atom is a hydroxyl, an amine, asulfonyl, a carboxyl, a halogen, or a combination thereof.
 18. Themethod of claim 16 wherein any hot gases or solids that do not distillout as a useable by-product are either to be further scrubbed and safelydisposed of, or recirculated into the carbonizer for reprocessing.